Host nation Japan easily beat Australia as the sports program at the delayed Tokyo 2020 Olympics finally got underway with a softball game in disaster-wracked Fukushima on Wednesday.

Japan's 8-1 victory, in a sport returning to the Olympic fold for the first time since 2008, took place two days before the opening ceremony of the pandemic-delayed Games.

Spectators were absent under the stringent coronavirus measures in place for an Olympics that is facing widespread opposition from the public in Japan, where infections are rising.

Japan have had to wait 13 years to defend the title they won at the 2008 Beijing Olympics and they dominated their Australian opponents in Fukushima, site of the tsunami-triggered nuclear disaster in 2011.

Their toughest challenge is likely to come from the United States, who play Italy in the second game on Wednesday.

Meanwhile, Australian showjumper Jamie Kermond was provisionally suspended from the Tokyo Olympics after testing positive for cocaine, team officials said on Wednesday.

The 36-year-old returned a positive A-sample for a cocaine metabolite on June 26 following a test by Sport Integrity Australia.

"Mr. Kermond is prohibited from participating in any WADA-compliant event, including the Tokyo 2020 Olympic Games, while the provisional suspension is in place," Equestrian Australia said in a statement.

According to Australian reports, Kermond did not travel with the rest of the team when they flew to Tokyo on Tuesday.